EP 0 898 780 B1 discloses a magnetically actuated circuit breaker for medium voltage applications in the range between 1 and 72 kV of a high current level. A single electromagnetic actuator drives a common jackshaft. This jackshaft internally couples the actuator force to the moving electrical contacts of each vacuum interrupter on all three poles through insulated push rods.
The electromagnetic actuator consists of a bistable magnet system, in which switching the armature to the relative positions are affected by the magnetic field of an electrically excited coil. The magnetic latching required holds contacts together during faults. A permanent magnet arrangement holds the ferromagnetic armature in one of the two limit positions corresponding to ON and OFF position respectively. In the ON position, the electrical contacts of the vacuum interrupter are opened; in the OFF position, these electrical contacts are closed.
All main parts of the known circuit breaker need their own housing, especially the actuator part, the three pole parts and the operating mechanism, including the jackshaft. During the manufacturing of the circuit breaker, all these housings have to be assembled one to another by screwing. This construction principle causes big geometrical dimensions of the circuit breaker device.